Analog-to-digital conversion (ADC) is often used to sample analog signals so that such signals may be digitally represented. The need for digital representation of analog signals arises in a variety of applications such as digital communication receivers.
A variety of techniques to perform ADC are well known in the art. Two common techniques include the successive approximation (SA) ADC and the flash ADC circuit. An SA ADC circuit generally produces a digital representation by processing an analog input signal through successive steps, at each step a comparison is performed to get a successively more accurate digital representation of the analog input signal. In a typical flash ADC circuit, an analog input signal value is compared with various reference levels, all at once, using multiple comparators. All other things being equal, because in a flash ADC circuit the signal is simultaneously compared with different reference levels in a single step, instead of in multiple steps as in an SA ADC, a flash ADC circuit may typically produce a digital representation of the analog signal with a lower latency than in a SA ADC circuit. Therefore, the flash ADC technique is generally considered more suitable for a high-speed application.